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THE AMERICAN TETRAGONOPTERINAE. 



209 



Specimens examined. 



Head 3.5-3.7; depth 2.5 or 2.6; D. 11; A. 18 to 21; scales 6 to 7-31 to 34-4 

 to 5; eye 2.7 to 3 in the head. Interorbital a httle more than the eye, 2.2 in the 

 head. 



Compressed, depth of the head at base of the occipital process 1.5 in the 

 greatest depth. Preventral region rounded, without complete median series of 

 scales. Predorsal region usually with a regular series of 11 to 14 median scales. 



Occipital process 6 in the distance from its base to the dorsal, bordered by 

 2 scales. Interorbital nearly flat. Frontal fontanel triangular, as wide as the 

 parietal and three fourths as long as the parietal without the occipital groove. 

 Second suborbital in contact with the preopercle below and behind. Maxillary 

 equal to the eye, mandible a little longer than the eye, 2.1 in the head. Mouth 

 large, snout very short. Premaxillary with three to five tricuspid teeth in the 

 outer row, and five 3- to 5-pointed teeth in the inner row. Maxillary rarely 

 without teeth, usually with one small 3- to 5-pointed tooth. Dentary with 

 a graduated series of four or five 3- to 5-pointed teeth followed by one or two 

 small, tricuspid teeth and five or six very minute conical ones on the side. 



Gill-rakers 7+9. 



Anal sheath of about nine scales covering the bases of the first 10 rays. 

 Lateral luie with pores developed on the first 5 to 7 rays. 



Origin of the dorsal the length of the eye nearer to the caudal than to the 

 snout, penultimate ray 2.5 in the longest, which is 4.25 in the length. Caudal 

 a httle longer than the head. Origin of the anal on the vertical from the fifth 

 to eighth dorsal rays. Base of anal convex. Anal subtruncate or only slightly 

 emarginate, the longest ray 1.5 in the base. Ventrals on the vertical from the 

 fourth scale in front of the dorsal. Ventrals just reaching the anal. Pectorals 

 little more than just reaching the ventrals. 



' Without the caudal; pectorals archaic. 



